scholarly journals Increased susceptibility of cystic fibrosis airway epithelial cells to ferroptosis

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Pramila Maniam ◽  
Ama-Tawiah Essilfie ◽  
Murugan Kalimutho ◽  
Dora Ling ◽  
David M. Frazer ◽  
...  

Abstract Background Defective chloride transport in airway epithelial cells (AECs) and the associated lung disease are the main causes of morbidity and early mortality in cystic fibrosis (CF). Abnormal airway iron homeostasis and the presence of lipid peroxidation products, indicative of oxidative stress, are features of CF lung disease. Results Here, we report that CF AECs (IB3-1) are susceptible to ferroptosis, a type of cell death associated with iron accumulation and lipid peroxidation. Compared to isogenic CFTR corrected cells (C38), the IB3-1 cells showed increased susceptibility to cell death upon exposure to iron in the form of ferric ammonium citrate (FAC) and the ferroptosis inducer, erastin. This phenotype was accompanied by accumulation of intracellular ferrous iron and lipid peroxides and the extracellular release of malondialdehyde, all indicative of redox stress, and increased levels of lactate dehydrogenase in the culture supernatant, indicating enhanced cell injury. The ferric iron chelator deferoxamine (DFO) and the lipophilic antioxidant ferrostatin-1 inhibited FAC and erastin induced ferroptosis in IB3-1 cells. Glutathione peroxidase 4 (GPX4) expression was decreased in IB3-1 cells treated with FAC and erastin, but was unchanged in C38 AECs. Necroptosis appeared to be involved in the enhanced susceptibility of IB3-1 AECs to ferroptosis, as evidenced by partial cell death rescue with necroptosis inhibitors and enhanced mixed lineage kinase domain-like (MLKL) localisation to the plasma membrane. Conclusion These studies suggest that the increased susceptibility of CF AECs to ferroptosis is linked to abnormal intracellular ferrous iron accumulation and reduced antioxidant defences. In addition, the process of ferroptotic cell death in CF AECs does not appear to be a single entity and for the first time we describe necroptosis as a potential contributory factor. Iron chelation and antioxidant treatments may be promising therapeutic interventions in cystic fibrosis. Graphical Abstract

2021 ◽  
Vol 55 (5) ◽  
pp. 590-604

BACKGROUND/AIMS: Oxidative stress and infections by Pseudomonas aeruginosa (P. aeruginosa) are prominent in lungs of patients suffering from cystic fibrosis (CF). METHODS: The present study examines effects of P. aeruginosa on lipid peroxidation in human and mouse lungs, and cell death induced by P. aeruginosa in human airway epithelial cells. The role of the Ca2+ activated Cl- channel TMEM16A, the phospholipid scramblase TMEM16F, and the CFTR Cl- channel for ferroptotic cell death is examined. RESULTS: Lipid peroxidation was detected in human CF lungs, which correlated with bacterial infection. In vivo inoculation with P. aeruginosa or Staphylococcus aureus (S. aureus) induced lipid peroxidation in lungs of mice lacking expression of CFTR, and in lungs of wild type animals. Incubation of CFBE human airway epithelial cells with P. aeruginosa induced an increase in reactive oxygen species (ROS), causing lipid peroxidation and cell death independent of expression of wt-CFTR or F508del-CFTR. Knockdown of TMEM16A attenuated P. aeruginosa induced cell death. Antioxidants such as coenzyme Q10 and idebenone as well as the inhibitor of ferroptosis, ferrostatin-1, inhibited P. aeruginosa-induced cell death. CFBE cells expressing wtCFTR, but not F508del-CFTR, activated a basal Cl- conductance upon exposure to P. aeruginosa, which was caused by an increase in intracellular basal Ca2+ concentrations and activation of Ca2+-dependent adenylate cyclase. CONCLUSION: The data suggest an intrinsic pro-inflammatory phenotype in CF epithelial cells, while ferroptosis is observed in both non-CF and CF epithelial cells upon infection with P. aeruginosa. CF cells fail to activate fluid secretion in response to infection with P. aeruginosa. The use of antioxidants and inhibitors of ferroptosis is proposed as a treatment of pneumonia caused by infection with P. aeruginosa.


1995 ◽  
Vol 268 (1) ◽  
pp. C243-C251 ◽  
Author(s):  
M. E. Egan ◽  
E. M. Schwiebert ◽  
W. B. Guggino

When nonepithelial cell types expressing the delta F508-cystic fibrosis transmembrane conductance regulator (CFTR) mutation are grown at reduced temperatures, the mutant protein can be properly processed. The effect of low temperatures on Cl- channel activity in airway epithelial cells that endogenously express the delta F508-CFTR mutation has not been investigated. Therefore, we examined the effect of incubation temperature on both CFTR and outwardly rectifying Cl- channel (ORCC) activity in normal, in cystic fibrosis (CF)-affected, and in wild-type CFTR-complemented CF airway epithelia with use of a combination of inside-out and whole cell patch-clamp recording, 36Cl- efflux assays, and immunocytochemistry. We report that incubation of CF-affected airway epithelial cells at 25-27 degrees C is associated with the appearance of a protein kinase A-stimulated CFTR-like Cl- conductance. In addition to the appearance of CFTR Cl- channel activity, there is, however, a decrease in the number of active ORCC when cells are grown at 25-27 degrees C, suggesting that the decrease in incubation temperature may be associated with multiple alterations in ion channel expression and/or regulation in airway epithelial cells.


1995 ◽  
Vol 269 (2) ◽  
pp. C451-C456 ◽  
Author(s):  
E. M. Schwiebert ◽  
D. C. Gruenert ◽  
W. B. Guggino ◽  
B. A. Stanton

Previously we demonstrated that the heterotrimeric G protein, G alpha i-2, inhibits cystic fibrosis transmembrane conductance regulator (CFTR) chloride (Cl-) channels in human airway epithelial cells (E. M. Schwiebert, F. Gesek, L. Ercolani, C. Wjasow, D. C. Gruenert, and B. A. Stanton. Am. J. Physiol. 267 (Cell Physiol. 36): C272-C281, 1994, and E. M. Schwiebert, N. L. Kizer, D. C. Gruenert, and B. A. Stanton. Proc. Natl. Acad. Sci. USA 89: 10623-10627, 1992). The goal of the present study was to determine if G proteins also regulate outwardly rectifying Cl- channels (ORCC), a distinct class of Cl- channels regulated defectively by protein kinase A (PKA) in cystic fibrosis (CF). To this end, we used the patch-clamp technique to study ORCC in a normal human airway epithelial cell line (9HTEo-) that expresses CFTR and ORCC. Stimulation of G proteins with GTP and GTP gamma S decreased the single-channel open probability (Po) of ORCC, whereas inhibition of G proteins by GDP beta S increased the Po. Moreover, pertussis toxin (PTX), an uncoupler of Gi and G(o) subclasses of heterotrimeric G proteins, also increased the Po. Purified G alpha i-2 decreased the Po. In contrast, other PTX-sensitive G proteins, G alpha i-1, G alpha i-3, and G alpha o, had no effect on Po. We propose that G alpha i-2 couples to a receptor whose agonist negatively regulates ORCC in human airway epithelial cells.


1998 ◽  
Vol 274 (6) ◽  
pp. L893-L900 ◽  
Author(s):  
Gerene M. Denning ◽  
Michelle A. Railsback ◽  
George T. Rasmussen ◽  
Charles D. Cox ◽  
Bradley E. Britigan

Pseudomonas aeruginosa, an opportunistic human pathogen, causes both acute and chronic lung disease. P. aeruginosa exerts many of its pathophysiological effects by secreting virulence factors, including pyocyanine, a redox-active compound that increases intracellular oxidant stress. Because oxidant stress has been shown to affect cytosolic Ca2+concentration ([Ca2+]c) in other cell types, we studied the effect of pyocyanine on [Ca2+]cin human airway epithelial cells (A549 and HBE). At lower concentrations, pyocyanine inhibits inositol 1,4,5-trisphosphate formation and [Ca2+]cincreases in response to G protein-coupled receptor agonists. Conversely, at higher concentrations, pyocyanine itself increases [Ca2+]c. The pyocyanine-dependent [Ca2+]cincrease appears to be oxidant dependent and to result from increased inositol trisphosphate and release of Ca2+from intracellular stores. Ca2+plays a central role in epithelial cell function, including regulation of ion transport, mucus secretion, and ciliary beat frequency. By disrupting Ca2+homeostasis, pyocyanine could interfere with these critical functions and contribute to the pathophysiological effects observed in Pseudomonas-associated lung disease.


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